Accession Number : ADA193707
Title : Inductions of Superoxide Dismutase by Ultraviolet Irradiation and by Manganese.
Descriptive Note : Final rept. 1 Dec 84-30 Nov 87,
Corporate Author : DUKE UNIV MEDICAL CENTER DURHAM NC DEPT OF BIOCHEMISTRY
Personal Author(s) : Fridovich, Irwin
PDF Url : ADA193707
Report Date : 01 Feb 1988
Pagination or Media Count : 2
Abstract : We have set out to study the inductions of superoxide dismutase and we have done that and a variety of other related projects. We find that the E. coli MnSOD gene is controlled by a repressor protein which can exist in two states i.e. reduced or oxidized. In the reduced state it blocks transcription of the MnSOD gene and in the oxidized state it does not. In soluble extracts of E. coli the repressor can be reduced by glutathione but not by cysteine and by NADPH but not by NADH. The redox active component of the repressor could be either a transition metal cation such as iron or a disulfide/thiol couple. This cannot yet be decided. The protein coded for by the MnSOD gene is first released in the form of an interactive precursor, distinct from the apoprotein and is then converted to the apoprotein. Final metal insertion to produce the active holoenzyme occurs much more readily under aerobic than under anaerobic conditions. As a consequence the inactive apoprotein, or a form with a metal other than manganese at the active site, accumulates under anaerobic conditions unless the medium is markedly enriched with Mn(II).
Descriptors : *ENZYME CHEMISTRY, *MANGANESE, *SUPEROXIDES, ANAEROBIC PROCESSES, CATIONS, CYSTEINE, GLUTATHIONE, INTERACTIONS, IRON, IRRADIATION, OXIDATION, OXIDATION REDUCTION REACTIONS, OXIDOREDUCTASES, PRECURSORS, PROTEINS, REDUCTION, SITES, SOLUBILITY, TRANSITION METALS, ULTRAVIOLET RADIATION
Subject Categories : Organic Chemistry
Distribution Statement : APPROVED FOR PUBLIC RELEASE